Electric snap switch



Aug. 17, 1943. G.' J; MEUER 2,326,874

ELECTRIC SNAP SWITCH Filed Oct. 2O, 1942 3 Sheets-Sheet l Aug. 17, 1943.G. J. MEUER 2,326,874

ELECTRIC SNAP SWITCH 3 Sheets-Sheet 2 Filed 061;. 20, 1942 55 55 445 fac44c 565 a f c az 47A 45 45 57 56 Y 14 f maw/1 Aug. 17, 1943. G. J. MEUERELECTRIC SNAP SWITCH 3 sheets-sheet` s Fild oct. 2o, 1942 Patented Aug.17, 1943 2,326,874 ELECTRIC sNAr SWITCH George J. Meuer, Milwaukee,Wis., assgnor 'to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation ofDelaware Application October 20, 1942, Serial No. 462,733

13 Claims.

This invention relates to improvements in electric snap switches.Although not limited thereto,

vthe invention is particularly applicable to so-v called low travellimit switches.

A primary object of the invention is to improve and simplify the detailsof construction and asv sembly of the parts and the operation of snapswitches of the Character herein contemplated.

Another object is to provide such a switch the parts of which areofrugged and durable construction and not likely to get out of order,while at the same time providing the desired high degree of sensitivitythereof to a force intended to operate the same.

Another object is to provide a. group of switch parts which may becombined in various ways to provide switches having various differentelectrical characteristics.

Another object is to provide a novel form of insulating and supportingcasing for the switch mechanism.

Another object is to provide novel means for effecting adjustment ofcertain of the switch parts relatively to each other to compensate forpossible slight inaccuracies in the size and/or shape of the switchparts.

Another object is to provide novel means for insuring maintenance of thefactory adjustment of the switch.

Another object is to provide novel forms of alternative switch contactsand stop plates to afford either a large or a small gap between the`contactor and the stationary contact or contacts.

Another object is to provide a small number of additional or substituteparts to enable production of a manually operable pushbutton switchhaving the various desired electrical characteristics aforementioned.

Various other objects and advantages of the invention will hereinafterappear.

The accompanying drawings illustrate certain embodiments of theinvention which will now be described, it being understood that theembodiments illustrated are susceptible of modification in respect ofcertain structural details thereof without departing from the scope ofthe appended claims.

In the drawings,

Figure 1 is a side elevational View (actual size) of a single pole,double throw (or three-point) low travel limit switch constructed inaccordance with my invention, the switch having a relatively small arcgap between the contactor and the respective stationary contacts, ashereinafter described.

Fig. 21s a top plan view of the switch shown in Fig. 1, with theinsulating cover and insulating plunger removed.

Fig. 3 is a sectional View, on the line 3--3 of l Fig. 2', with all ofthe switch parts assembled.

Fig. 4 is abottom plan view of the switch shown in Figs. 1 to 3.v4 i

Fig. 5 is a transverse section, on the broken lines- 5 or Fig. s.

Fig. 6 is a transverse section, on the broken line 6-6 of Fig. 2.

Fig. 7 is a transverse section similar to Fig. 6,

but illustrating a modification wherein onlyone (upper) stationarycontact is employed, vthe same being specially formed to provide arelatively large arc gap when the contactor is moved to its normallydisengaged position.

Fig. 8 is a fragmentary bottom plan view of a V p engagement of thelatter from the Contact.

, Fig. 10 is a fragmentary bottom plan view of a switch likethat shownin Fig. 9.

Fig. 11 is a top plan view, with the insulating cover and insulatingplunger removed, of a modified form of switch mechanism, requiring aslightly modified form of insulating base.

Fig. l2 is a sectional view, on the line |2--l2 of Fig. 11.

Fig. 13 is a top plan view, actual size, of a single pole, single throw.pushbutton switch of the momentary on type, said switch embodying mostof the structural features of the switch of Figs. 1 to 6, but modifiedto provide a relatively large arc gap, and having a different positionfor the insulating plunger.

Fig. 14 is a sectional view, on the line |4|4 of Fig. 13, illustratingthe novel form of the pushbutton and the manner of supporting the samerelatively to the switch.

Fig. 15 is a fragmentary view, partly in side elevation and partly invertical section, of a different form of pushbutton operated snapswitch, of the momentary on type shown in Fig. 14, the insulating covermember of the switch being modified to provide for attachment of themetal bushing which acts as a support and guide for the pushbutton. a

Fig. 16 is a fragmentary bottom plan view of a single pole, single throwswitch, including a bus member or connector which provides forpositioning of the wiring terminal member, for the stationary contact,at one side of the bottom surface of the base, if 'desired for specialwiring, and

Fig. 17 is a top plan view of an insulating stop plate or spacer whichis employed in a switch like that of Figsl and 16.

Referring first to the low travel limit switch of the snap type shown inFigs. 1 to 6, the numeral 20 designates the base, which is molded to theform illustrated from any suitable insulating material, such as BakeliteBase 20 is preferably of relatively long substantially rectangularcontour, as shown, and the same is provided in its upper surface with arecess 20 extending throughout the major portion of the length and widththereof, the peripheral wall 20 of said recess having a iiat upper edge.A molded insulating cover member 2|, preferably composed of Bakelite,has a downwardly opening recess 2| the fiat lower edge of whoseperipheral wall is adapted to seat against the uppe edge of Wall 20, 1

Base 2l! and cover member 2| are provided at the midwidth of one endwith alined passages 20 andl 2|c to accommodate the shank of a rivet 22of suitable metal, preferably aluminum, the head of which is positionedin the countersinkA 2|d in the upper surface of cover 2| and the hollowend of which is upset within the countersink 2|)d in the lower face ofbase 20.

Cover 2| is provided adjacent one end of recess 2| with an integralcentrally located extension 2|e of approximately elliptical form inhorizontal cross section, said extension preferably having in its flatlower face substantially ush with the lower face of peripheral wall 2lb.

Cover 2| as molded is provided with a passage 2|f of circular form incross section, which is adapted to accommodate and guide the cylindricalupper end portion 23 of a plunger having a cylindrical enlargement orhead 23". The lower end portion 23c of head 23h is preferably of convexform, as shown at 23d (Fig. 3), and the upper end of portion 23'r of theplunger is also preferably of convex form, as shown at 23.

Cover 2| is also preferably provided with a recess 2|U extendingupwardly a predetermined distance from the lower surface of extension2|, for a purpose to be later described.

Cover 2| is provided adjacent the other end of recess 2| with anotherintegral extension 2|h whose flat lower face is offset upwardly asubstantial distance from the lower edge of peripheral wall 2|b.Recesses 2|i and 2|J extend upwardly a substantial distance from thelower face of extension 2|h, and are produced by the operation ofmolding the cover 2|. The recess 2|l is utilized as a guide or templateto facilitate drilling of a passage to the outer face of cover 2| whenthe latter is to be used for another form of switch disclosed herein(see Fig. 14).

Base 2| is provided at its right-hand end (Fig. 2) with a pair ofpassages 2|)e and 20f, and cover 2| is provided with a pair of passages(not shown) to be alined therewith, av pair of rivets 22 having theirheads located in countersinks in cover 2|, one of which is shown at 2|kin Fig. 1, and having their hollow ends upset in countersinks 2lig and2|)h in the lower fac'e of base 20 (Figs. 1 and 4),. The three likerivets 22 are adapted to hold base 20 and cover 2| firmly in assembledrelationship to each other.

The switch mechanism located within base recess 20 comprises a punchedand stamped sheet metal bracket the horizontal portion 24 ofvwhieh seatsflatwise upon the bottom wall of said recess at one end of the latter.Portion 24B of a width only slightly less than the width of recess 20,and said portion is provided adjacent opposite ends thereof withperforations alined with passages of corresponding size to accommodatetheshanks of rivets 25, 25 of brass, or other metal of good electricalconductivity. The shanks of rivets 25 also penetrate openingsofcorrespending size formed in a terminal plate 26 located within acountersink 2|)l in the lower face of base 20, and the hollow ends ofsaid shanks are upset, as shown in Figs. 4 and 5, to hold portion 24 andplate 26 in assembled relation to base 20 and in electrically connectedrelationship to each other. Plate 26 is provided with an extruded andtapped opening 26 (Fig. 3) to accommodate the shank of a wiring terminalscrew 2l, base 20 being provided with a recess 2|)J to afford clearancefor said shank.

Portion 24 of the bracket is of approximately T-shape (Fig. 2), therelatively narrower extension 24b thereof being located within thecorrespondingly narrower portion of recess 20, and an end of saidextension being bent upwardly at substantially a right angle thereto, asshown at 2lic (Figs. 2, 3, and 5). Said end 24 is deformed at themid-point of its width to provide a. vertical. knife-edge bearing 24d,and said end is provided with alined, substantially rectangular notches24e, 24t opening to Opposite side edges thereof, as best illustrated inFig. 5.

A flat lever 28 (Figs. 2' and 3) is provided at its right-hand end witha relatively wide'rectangular notch 28a, the intermediate portion ofwhose inner edge is adapted to abut or bear against the aforementionedvertical knife-edge 24d (see Fig. 2). Notch 28 also provides the pair ofspaced arms or lugs 28b and 28 which respectively t within the notches24 and 241' aforementioned, thus providing a pivotal suppOrt I for lever28.

Lever 28 is provided at its other end with an integral portion 28d bentdownwardly therefrom at approximately a right angle with respect thereto(see Fig.- 3), said portion 28d having a centrally located relativelynarrow, substantially rectangular opening 28e, which is adapted toaccommodate the relatively small lug 29 which is preferably located inthe plane of the main body portion 29b of apunched and stamped sheetmetal contactor-carrying member. The portion of said member between lug29 and portion 29b is bent to substantially V-form in cross section, asshown in Fig. 3, the portion 29 of said V being adjacent lug 29, and ofa width corresponding to the width of lever 28, whereas the portion 29dof said V is provided with integral lateral extensions or arms 29e and291,l which are notched at their respective forward edges, as shown at29 and 29h (Fig. 2), to accommodate and assist in retaining the hookedends of a pair of coiled tension springs 30, 30.

The forward end of'portion 29 is preferably of arcuate contour, as shownat 29 in Fig. 2, and said end is provided with a perforation (see Fig.6) to accommodate the shank of a rivet, the somewhat hemispherical headfof which is designatedl by numeral ill!b (Fig. 3) said shank being upsetor formed, on the opposite side of portion 29h, as shown at 30. The head3|)b and upset shank 3B form the tips of the contactor, which is thusprovided with a. good mechanical and electrical connection with portion29b of the carrier. Rivet asaasu 3 3|)b is preferably composed ofsilver, or a compound including silver, to provide contactor of goodelectrical conductivity, low contact resistance, and long life.

As best illustrated in .7i-g. 2, the other hooked ends of springs 30, 30are respectively engaged with the walls o'f relatively small openings248, 24h in lugs Mi and 2lij formed integrally with the aforementionedportion 24E.

Inasmuch as the switch of Figs. 1 to 6 is of the single pole, doublethrow, or three-point, type,

I provide a pair of upper and lower stationary contacts 3|, 3|, whichare preferably of identical form;v each having opposite end portions ofsubstantially .circular contour, with an integral, straight-sided neckportion therebetween. One end of each contact is perforated toaccommodate the shank of a rivet-the lower contact 3| seating upon thebottom wall of recess 20a and having the rivet head 32 overlying theyperforated end portion thereof; the relatively short shank 32a of whichrivet (Fig. 6) penetrates an alined passage formed in base 20 and aperforation in a terminal plate 33, and has its hollow end upset oversaid plate to secure the latter to the lower face of the base. In likemanner the upper contact 3| is seated upon a ledge 20k, offsetdownwardly from the upper surface of base 20; the head 34 of arelatively longer rivet overlying the perforated end of said uppercontact, and the shank 34a of said rivet penetrating an alined passageformed in base 20 (Fig. 6) and a perforation in a second terminal plate33, and having its hollow end upset over said terminal plate. Terminalplates 33, 33 have extruded and tapped openings (not shown) toaccommodate the shanks of a pair of screws 21, 21 to provide forattachment of circuit wires; the lower face of base 20 being providedwith recesses (not shown) to provide clearance for the shanks of saidscrews last mentioned.

The contacts 3|, 3| are preferably provided with contact portions ortips of silver or a compound including silver; and in practice I preferto provide this feature by punching contacts 3| on the bias from a metalstrip a portion of which is of bimetallic construction. Thus in Figs. 2and 3 the silver portions or tips of the contacts are arranged to faceeach other, and are designated by numerals 3| a, 3| a; the main bodyportions of contacts 3|, 3| preferably consisting of brass or othersuitable metal of lower cost than silver.

In order to bias lever 28 toward its upper extreme position, shown inFig. 3, I prefer to provide a coiled compression spring 35, whose lowerend is seated and centered within a shallow subrecess 221 of circularcontour in the bottom wall of recess 20a, the upper end of spring 35being adapted to press against the lower face of lever 28, to normallythrow the latter over center against the bias of springs 30, 30.

The'degree of upward displacement of lever 23 is limited by engagementof the upper surface thereof with the lower surface of the head 36a of ascrew, lever 28 having a substantially elliptical opening to provideclearance between the same and the screw shank. The portion 36b of thesc rew shank has threaded engagement with a tapped opening or passage23m formed in base 20-by the molding operation. Passage 2|!m extendsfrom the bottom wall of recess 20a through the upper end wall of arelatively large recess 20n (Fig. 3) of cylindricalform which opens tothe lower surface of base 20. As shown in Fig.

^ rier 29b and tension springs 30, 30. In practice or tip 30h is snappedinto engagement with the silver tip portion 3|.a of the upper stationarycontact 3|; thereafter the screw is withdrawn (the head 36a lifted) tosuch an extent that the contactor tip 30 is snapped into engagement withthe silver tip 3|tl of the lower stationary contact. Thereafter thescrew is further withdrawn by effecting another complete turn thereof,so that the parts are in the relative positions thereof shown in Fig. 3.In order to prevent any further withdrawal of the screw (eitheraccidental or otherwise) I prefer to bend, as illustrated, that portion36c of the screw shank which projects into recess 20. Such bending maybe effected by inserting a suitable tool, such as a tube to closely t.around the screw shank, and then manually appIying a suitable force toeffect the desired degree of bending. This definitely prevents upwarddisplacement of the screw.

Also, in order to prevent downward displacement of the screw afteradjustment thereof and bending of the exposed lower end of its shank, Iprefer to ll the recess 2|)u with a wax or cement of suitable hardness,toughness and tenacity or adhesiveness, as indicated at 31 in Figs. 3and 4, the cylindrical body of wax cooperating with the bent end of thescrew shank to prevent rotation of the screw in a downward direction.

As shown in Figs. 1, 3 and 4, the recess 2l)u is surrounded for aportion of its depth by a projecting wall 20 formed integrally with thebottom face of 'base 20, sai-dintegral wall being extended toward theleft-hand nd of base 2|), as

shown at 201 to provide a barrier between theA pair of screws 21, 21 atsaid end. The filling of wax within recess 2|)n is preferably of thesame color as the material of base 20 (which is preferably black),wherefore the finished appearance of the lower face of the base isaccentuated.

As best illustrated in Fig. 4, the lower face of base 20 is recessed at201 and 2|)r to accommodate the terminal plates 33, 33, and recesses(not shown) are also provided to accommodate the Shanks of the screws21, 21 associated with said plates.

As best illustrated-in Fig. 3, the bottom wall of recess 2lia is furtherrecessed at 20s and 2N to insure adequate clearance for the lever 28,carthe aforementioned adjusting screw is provided with a reduced or neckportion 36d between head 36'.l and threaded portion 35b of the shank, toavoid interference between the screw shank and the coils of spring 35,and to minimize the required size of the elliptical clearance opening inlever 28.

The switch as a whole may be mounted in any suitable manner, the base 20being shown as provided with a pair of transverse passages 38, 39 (Figs.1 and 3) to accommodate the shanks of bolts or screws for attaching theswitch to a suitable support.

'I'hemanner of operating the switch will be apparent to those skilled inthe art, but it may be pointed out that with the parts in the respectivepositions thereof shown in Fig. 3 the end 25@ of the insulating plungeris adapted to be engaged by any suitable or well known form of operatingmember, such as a lever, cam, or the like (not shown) which is movabletoward cover Et in response to a change in a given condition eitherycontrolled or to be controlled by a translating device which is in turnsubject to control by the switch. Upon a predetermined degree of inwardmovement of plunger 23a the end 23d thereof acting against lever 28causes movement of the left-hand end of the latter so that the point ofengagement thereof with lug 29 of the carrier 29b is moved belowtheplane of engagement of the left-hand ends of springs 30, 30 with arms2lie and 25|t of carrier 29h, whereupon the latter snaps upward toeffect disengagement of tip 30a from the lower stationary contact andengagement of the tip 3|)b with the upper stationary contact.

As will be noted, only a relatively short length of plunger 23ELprojects upwardly beyond cover 2|, whereas only a portion of thepossible downward movement of the plunger is required to eiect theaforedescribed snap operation of the switch. The balance of the downwardmovement of the plunger is accommodated by the lost motion providedbetween the switch parts, which will at most merely cause a rockingmotion of the contact tip then engaged with a stationary contact withoutsubstantially affecting the degree of contact pressure. Excessive inwardmovement of the plunger 23 will be prevented by engagement of theoperating member with the surface of cover 2|. pressure upon the plungerspring 35 will act automatically to lift lever 28 against the bias ofsprings 30, so that the carrier 29b will be snapped from the positionjust described to its normal position shown in Fig. 3.

In the modification shown in Figs. '1 and 8 the parts not illustratedmay b e identical with the corresponding parts of Figs. 1 to 6, whereasmost of the parts shown in Figs. '1 and 8 are identical with thoseaforedescribed and such identical parts have been given like numerals ofreference. However, the switch shown in Figs. 'l and 8 is adapted toprovide a large arc gap upon disengagement of the contactor tip 30 fromthe upper stationary contact; and the switch is of the normally opentype, wherefore the lower stationary contact is omitted.- Instead of alower contact I prefer to employ a fiat sheet metal plate 40 (preferablyof cold rolled steel) as shown in Fig. 7. Plate 40 is of the same shapeand dimensions as the aforedescribed contacts 3|, and serves to insureproper spacing vof the contactor tip 3|llL and its carrier from thebottom wall of recess 2|) in the normal or open position of the switchparts. The hollow lower end of rivet 32*l is upset over a washer 4|; oneof the terminal plates 21 of Figs. 1 to 6, of course, not beingrequired.

'I'he upper stationary contact 3|x of Figs, 'I and 8 is quite similar tothe contact 3| aforedescribed. the downwardly facing layer 3|y (Fig. 1)of silver or the like extending throughout the lentire area of contact3|x and being functionally similar to the layer 3| of contact 3|aforedescribed. Moreover, the intermediate or neck portion of contactEilx is bent upwardly as shown to provide the large arc gap(approximately .062 inch) between the stationary contact and contactortip 30b in the normal position of the latter illustrated. In a switchlike that of Figs. 1

Upon release of the operating to 6 the relltively smallarcgap is equalto approximately .029 inch. Wh'ere auch large arc gap is provided thescrew 36* (Fig. 3) is adjusted lin the manner aforedescribed, exceptthat after withdrawing the same to the point at which the contactor issnapped to its lower position, the screw is given two complete .turnsto, further raise the screw head, instead of the one complete turnemployed with switches having said small arc gaps.

It will be apparent to those skilled in the art' that the switch ofFigs. 7 anda mightbe modiiied by providing a lower stationary contact(similar to 3l cf Figs. 1 to 6, but preferably having a silver layerextending throughout ,its entire area, see Fig. 9), instead of plate4|), land bysubstituting a wiring terminal plate 33 and screw 21l forwasher 4|. Such a switch would then be functionaily like the switch ofFigs. 1 to 6, but/ l would differ therefrom in `respect of providing thelarge arc gap upon movement of the contactor to its alternatepositions.l

In Figs. 9 and 10 I have illustrated a large arc gap snap switch quitesimilar to that of Figs. 7 and 8, but of the normally closed type, witha special form of stop plate to limit the degree of movement of thecontactor to "open position. Thus the special stop plate 42, whichispreferably punched and stamped from a sheet of cold rolled steel, isthe same in shape and dimensions as the upper stationary contact 3|x ofFig. 7, the upwardly offset stop portion thereof providing the large arcgap when `thecontactor is disengaged from the lower stationary contact43. Contact 43 is of the same shape and dimensions as the contacts 3| ofFigs. 1 to 6,-but, as shown, has the layer 43u of silver or the likeextending throughout the entire area thereof. As shown in Figs. 9 and 10the hollow -end of rivet shank 32n is upset over the terminal plate 33,which is provided with a binding screw 21; whereas the hollow end ofrivet shank 34H5 upset over the metal washer 4|.

In the modification illustrated in Figs ll and I2 the cover 2| andplunger 23 may be identi- .44d communicating therewith, the sub-recesses44h and 44 affording adequate clearance for the adjacent movableelements of the switch mechanism.

The bracket 45 of the switch mechanism is secured to the bottom wall ofrecess 44a by rivets 25, 25, which have their hollow ends upset over thelower surface of terminal plate 26 (Fig. 12) in the manneraforedescribed, plate 25 having a binding screw 21 associated therewith.A relatively narrow portion 45*i of bracket 45 is located within thecorrespondingly narrower portion of recess 44, and the end 45b is bentupwardly from portion 45* at substantially -a right angle thereto. Saidupstanding end is deformed at the mid-point of its width to provide thevertical knife edge bearing 45f, and the same is laterally notched (asdescribed in connection with the device of Figs. 1 to 6) to provide apivotal bearing for the notched right-hand end of' a lever 45.

Lever 46, as best illustrated in Fig. ll', ,is of substantially Y-shape,the arms 46 and 4Gb being spaced from each other in a common plane, andthe forward ends thereof being bent downwardly therefrom atapproximately a right angle, as shown at 46c and 46d. Each of said ends46c and 46d is provided a hemispherical depression in the outer orforward face thereof, as indicated in dotted lines at 46 and 46f, toprovide bearings modate the portion 23'L of the plunger, whereas thepassage 2|t is preferably tapped to accommodate the shank 49 of a screwwhich shank for the correspondingly spaced pointed 'ends of the arms 41*and 41b of a flat, punched sheet metal contactar-carrier 41. Carrier 41is provided at its forward end with a perforation (not shown) to providefor attachment thereto of a rivet of silver or the like, the head 30h ofwhich is adapted to act as a tip for engagement with the upperstationary contact 3|, and the upset shank portion 30 of which isadapted to act -as a tip for engagement with the lower stationarycontact 3|, said contacts having tips or layers of silver, asdescribed'inconnection with Figs. 1 to 6. i l

Carrier 41 is cut away at its inner end between arms 41m and 41h, thearcuate edge of said cut away portion being designated by numeral 41,said cut away providing clearance for the vertical coiled portion 48 ofa tension spring 48, one straight arm of which is provided with a hookedor curved end 48b which is adapted to engage the wall of a relativelysmall circular openirlig'41d in carrier 41.

The other straight arm of spring 48 is provided with a hooked end 48cadapted to engage the wall of an` opening 45 in the upwardly bentrelatively narrow forward end or extension 45d of bracket 45. The arms46n and 46b are spaced sufllciently to provide the necessaryv clearancebetween the same and bracket end 45d. Lever 46 is provided with anupwardly embossed or offset portion of circular contour, as shown at468, the lower surface of which portion is adapted to accommodate andcenter the upper end of a coiled compression spring 35, like that ofFigs. 1 to 6.

Portion 46ir is provided with a relatively large opening 46h (Fig. 12)to provide adequate oscillating clearance between lever 46 and thereduced or neck portion 3bd of the adjusting screw, the head 36 of whichoverlies said lever to limit the degree of upward displacement thereof.I The portion 36b of the screw shank has threaded engagement with thetapped opening or passage 44e formed in base 44, it being noted thatsaid opening communicates with the downwardly opening cylindrical recess44t (Fig. 12) at the righthand side of the center of the latter. Thelower end portion 36c is therefore bent toward the left after adjustmentof the screw, as shown in Fig. 12. As shown in Fig. 12 bracket, 45 isembossed to provide a downwardly offset recess to receive and center thelower end of spring 3.5, said offset being perforated to provideclearance for the shank 36b of said adjusting screw. The recess 44t ispreferably filled with wax or cement, as indicated at 31, for thepurpose hereinabove set forth. The operation of the switch of Figs. l1and l2 will be obvious from the foregoing description of the operationof the switch of Figs. 1 to 6.

In Figs. 13 and 14 rhave uiustrad a manuany' operable pushbutton snapswitch of the single pole on and off type, the same being normallybiased to 01T position, wherefore the same is of the momentary on type.'I'hat is to say, the same is only on so long as the pushbutton issufficiently depressed. The switch mechanism employs the base 20, cover2|, plunger 23B, and most of the other elements of the switch of Figs. 1

penetrates an opening in the righthand end 5I)EL of a lresilient sheetmetal member 50, which vis preferably composed of phosphor bronze, a.lock washer 6| being preferably interposed between head 49 and saidportion 50, and said head 49 acting to clamp member 50 in position.

Member 60 extends toward the left and has a portion 5|)b (Fig. 14) bentdownwardly atsubstantially a right angle thereto, a portion 60cextending toward the left at substantially a right angle to portion 50h,and the free end thereof being bent upwardly at a slight angle, as shownat portion 23 of the plunger. Portion 50 of member 50 in part overlies aportion of the forward or left-hand end of lever 28, to provide a properoperating connection between the latter and the lower end 23of theplunger. Member Sealso serves to absorb or neutralize the weight of thepushbutton operating elements now to be described.

The pushbutton, designated in general by numeral 52, is carried by apunched and stamped sheet metal member, the fiat main body portion 53 ofwhich is spaced upwardly a predetermined distance from the switch cover2|. The means for spacing portion 53 preferably includes an integral endportion which is bent downwardly as shown at 53 and then inwardly asshown at 53b to overlie the left-hand end of cover 2|. Portion 53b isprovided with a tapped opening 53c overlying the alined passages 2 |cand 26 in cover 2| and base 20, the threaded shank of bolt 54 .beingadapted to take into'said tapped openings invbase 20 and .cover 2|, apair of tubular spacer members (one of which is shown at 56 in Fig. 14)being interposed between the lower surfaces of oifsets 53l and 53h andthe bottom walls of the pair of countersinks in the upper surface ofcover 2|. 'I'he ends of said screw- Shanks are preferably upset over theupper surfaces of offsets 53g and 53h, as shown at 55a, 55a in Fig. 13,to prevent accidentalloosening .of said bolts.

Portion 53 is provided at opposite ends thereof with tapped openings 51and 58 to provide for attachment of the switch to a suitable support, asby means of a pair of bolts or screws (not shown).

Portion 53 has formed therein a relatively large circular opening 53i(Fig. 14) which is concentric to the insulating plunger 23a of theswitch. A hollow cylindrical tube or bushing 59 has a reduced lower endinsertable downwardly with a close fit' into opening 531, said reducedend being spun or upset over the lower face of portion 53, as shown at59* to rigidly secure tube 59 in assembled position.

The pushbutton 52 consists of a sub-assembly including the cylindricalhollow metal member 6 2,sae,e74

52* having a closed upper end provided with a convex surface 52h, member52* having an outwardly projecting' peripheral flange 52c at its lowerend. A relatively heavy coiled compression spring 50 is interposedbetween theclosed upper end of member 52ai and the closed, flat lowerend wall li2i of a hollow metal member 52 which is adapted for slidingor telescopic movement within member 52a. Member 52 is of reducedoutside diameter for a predetermined distance above its lower end toprovide the peripheral shoulder 521; and a sheet metal member 52' havingan opening 52h to slidably accommodate the reduced lower end portion ofmember 52, but of a size to provide a peripheral abutment for theaforementioned shoulder 52, has an upstanding peripheral flange 52lwhich is bent inwardly over the upper surface of the aforementionedflange 52, as shown at 521. In practice the spring 60 is placed under apredetermined degree of compression prior to or as an incident to inwardbending of the portion 521 of the flange of member 52'.

After thus assembling the parts of pushbutton 52, the latter is insertedupwardly from the lower surface of portion 53 through the bushing 59,the flange 52 and the spun over portion 52! of flange 52i abuttingagainst the spun over portion 59* of bushing 59 to limit the degree ofupward movement of the pushbutton assembly.

As will be understood the pushbutton 52 is positioned as shownrelatively to portion 53 prior to attachment'thereof tothe switch bybolts 54 and 55, 55. The arrangement is preferably such that with theparts assembled as shown in Fig. I4 if the complete assembly wereinverted there would be no pressure of the pushbutton parts against theplunger 23n such as to cause any inward displacement thereof. It followsthat the resilient member 50 is 'adapted to function to absorb orcompensate for the weight of the parts of pushbutton 52 to avoid anyinward displacement of plunger 23* when the parts are in the normalpositionsA thereof illustrated; whereas member 50 serves also to insureproper cooperation of plunger 23' with respect to lever 28.

As illustrated in Fig. 14, the switch is preferably adapted to provide alarge arc gap, and I may therefore employ an upper stationary contact31x of the character aforedescribed in connection with Fig. '1, saidcontact having a layer 3ly on its lower surface extending throughout theentire area thereof, to insure a large current carrying capacity. Themetal stop member 40 in Fig. 14 may be identical with the correspondingelement of the switch of Fig. '7, the rivet 32* in Fig. 14 being upsetover a metal washer 4|, as described in connection with Fig. rI.

the device of Fig. 14, upon manual depression of pushbutton 52 thespring 50 acts to cause movement of the parts 52* and 52 as a unit toeffect depression of plunger 23e for operation' of the switch mechanismin the manner described in connection with Figs. 1 to 6. Upon ,continuedinward movement of pushbutton 52 the dat end portion .'i2d of member 52will engage the upper face of cover 2|, and thereafter member 52 willtelescope downwardly over member 52, against,

aforementioned screw is preferably filled with a black wax or cement toa plane flush with the upper surface of cover member 2 I.

In Figs. 15, 16 and 17 I have shown a manually operable pushbutton snapswitch of the normally open type, the same, in this respect, beingfunctionally like 4the modied form of switch shown in Figs. 7 and 8, andthe same being also like that shown in said earlier gures in respect ofthe provision of a large arc gap. However, whereas in Figs. 'I and 8 Iemploy a metal stop plate 40, in the device of Figs. to 17 I prefer toemploy an insulating stop plate 5I, preferably punched from a sheet ofreinforced Bakelite or similar material. 'I'he reason for this changewill be apparent upon comparison of Figs. 8 and 16.

Thus, whereas in Fig. 8 the rivet 32* is upset directly over theterminal plate 33, in Fig. 16 I interpe a bus member or connector 52between the rivets 34n and 32, the rivet 34l being upset over a washer4I, which may, if desired, be of brass, which clamps one end of the busmember in position and provides an electrical connection between saidparts, and the rivet 32|L (which penetrates th other end of bus member62) is upset directly over terminal plate 33 this position of theterminal plate being preferable to that shown in Fig. 8 to facilitatewiring and to insure adequate electrical clearance, in the event thatthe upper side of the switch (Fig. 16) is attached orclamped to a metalsupport or panel. Because of the electrical connection afforded by busmember 62 it is obvious that a stop plate 5i of insulation is required,to provide for interruption of the controlled circuit in the normalpositions of the several switch parts.

. Aside from the differences just mentioned, the base 20 and the partscarried thereby may be like those of the switch shown in Figs. 1 to 6,the corresponding parts illustrated having been given like numerals ofreference.

The insulating cover 63 (Fig. 15) differs from the cover 2|aforedescribed primarily in respect of the provision of a relativelylarge circular opening 53` which is concentric with that point on lever28 engaged by the convex end 23 of the plunger in the device of Figs. 1to 6. A cylindrical hollow metal bushing 64 has a lower end portion 54nof reduced diameter which is insertable downwardly through said opening63, the projecting part of said lower end being spun outwardly or upsetover the wall of the recess 63h in cover 53, as shown at 64b. A metalwasher 55 is preferably interposed between said recess wall and the spunover flange 64b to avoid possible iniury to the cover by the spinningoperation.

'Ihe manually operable pushbutton preferably consists of a substantiallycylindrical molded insulating member 66 which slidably ilts within andnormally projects a substantial distance upwardly beyond the bushing 54.Member 66 is preferably provided with a convex upper end 55, and thesame is provided with a lower end portion Gib of relatively largerdiametento provide a shoulder '56 which is adapted to abut or seatagainst the outwardiy'spun flange 64b to limit upward displacement ofthe pushbutton. Member 66 is provided in its lower end with a centrallylocated substantially cylindrical recess 56d which accommodates aportion of the length of a coiled compression spring 61, the lower endof said spring being arranged to engage lever 28 at the same point asthe lower end 23 of the plunger in the device cf Figs. 1 to 6.

As will be understood pushbutton 66 is inserted upwardly through bushing64, and the spring 61, in the normal positions of the assembled switchparts is compressed to a slight shown in Fig. 15)

Thus upon manual depression of pushbutton 86 the spring 61 is firstcompressed to a degree suiilcient tovovercome the aforementioned bias ofsprings 30 and 35, with resultant snap movement of contactor tip 30hinto engagement with the portion 3U of stationary contact 3IX. Furtherdepression of pushbutton 66 will be compensated for by increasedcompression of spring 61,whereas the convex surface 66 of saidpushbutton will be substantially flush with the upper end of bushing B4prior to direct engagement of the lower end ofl pushbutton 66 with lever28.

In this manner any excessive pressure upon lever 28 or other parts ofthe switch is effectively prevented.

As illustrated in Fig. 2^the upper stationary contact member 3| has theside edges of its neck portion fitted quite closely between a pair ofvertical wall portions which assist in defining the contour of the ledge20k upon which said contactor is adapted to seat. In like manner, oneside edge of the neck portion of the lower stationary contact 3ltsclosely against a vertical wall portion of base 20,'whereas the bottomwall of recess 20' is provided with an integral boss 28, shown as ofsubstantially cylindrical form, a portion of the periphery of which islocated closely adjacent the other side edge of said neck portion. Inthis manner properly alined positioning of the silver tip portions ofsaid contacts is initially provided and maintained.

Referring again to Fig. 3, it is desired to point out that theright-hand recess 2|g in cover 2l may be ,drilled or otherwise formed toprovide a passage extending through to the upper face ofcover 2|, thepassage thus formed being adapted to accommodate the plunger 23a (or asimilar actuating element) for engagement with lever 28 at a point moreclosely adjacent the right-hand, or pivotally supported, end of thelatter. With an actuating element so positionedl a greater amount ofpressure or force thereon is required to depress lever 28 for actuationof the snap switch mechanism, but at the same time the degree ofdownward travel or movement of the actuating element is substantiallylessened. When cover 2l is so modified, the aforementioned passage 2|Iis preferably filled with a black wax or cement to a plane flush withthe upper face of cover 2|.

In addition to the modification of cover 2l shown in Fig. 14, in respectof recess 2li, I may.

also modify said 4cover by drilling through both recesses 261 and 2l)j(either of the same size or smaller) to provide a pair of passages toaccommodate the shanks of a pair of rivets or the like (not shown) whichmay be utilized to fasten to the upper face of cover 2l one end of aleaf spring having an upwardly curved or bent free end portion overlyingthe upper end '23e of plunger 23a to provide for operation of the latterby means (not shown) well known in this art.

I claim:

1. In an electric snap switch, in combination, an insulating base, abracket secured thereto, a lever having an open pivotal connection withsaid bracket, a contactor having an open pivotal connection with saidlever, tension spring means attached jointly to said bracket and tosaid'contactor to maintain the aforementioned pivotal connectionsbetween said parts and to bias said contactor toward one extremeposition or the other according to the positionA of said lever, a pairof stop members arranged above and below said contactor to limit thethrowof the latterin each direction, a coiled compression springinterposed between said base and said lever to bias the latter away fromthe former, a screw having adjustable engagement with said base, thehead of said screw overlying said lever to limit the degree of movementthereof under said spring bias, at least one of said stop memberscomprising a stationary contact, a wiring terminal element electricallyconnected with said contact, a wiring terminal element electricallyconnected with said bracket, said wiring terminal elements being exposedat the lower face of said base, and means comprising a movable memberengageable with said lever to effect movement of the latter against saidspring bias thereof.

2. In an electric snap switch, in combination, an insulating base, ametal bracket secured to said base, a metal lever having at one endthereof an open pivotal connection with said bracket, a metal contactorhaving an open pivotal connection with said lever at the other end ofthe latter,l a plurality of stop members arranged in spaced relationshipto each other and at opposite faces respectively of said contactor, atleast one of said stop members comprising-a stationary contact, tensionspring means interposed between said bracket and saia contactor,said'spring means being adapted to bias said contactor into engagementwith one o1' another of said stop members according to the position ofsaid lever, means for limiting the movement of said lever in oppositedirections 'respectively, additional spring means for biasing said levertoward one of its extreme positions, and movable means engageable withsaid lever between the point of pivotal support thereof and saidcontactor to effect movement of the former toward its other extremeposition against the bias of said additional spring means, said tensionspring means being adapted upon such movements of saidl lever `towardopposite extreme positions to effect reverse movements of said contactorwith a snap action into engagement with said stop members alternately.

3. In an electric snap switch, in combination, an insulating base, asheet metal bracket secured to said base, a sheet metal lever having atone end thereof an open pivotal connection with said bracket, a sheetmetal contactor having an open pivotal connection with said lever at theother end of the latter, a pair of stop members arranged in spacedrelationship to each other and at opposite faces respectively of saidcontactor,

at least one of said stop members comprising a stationary contact,tension spring means interposed between said bracket and said contactor,said spring'means being adapted to bias said contactor into engagementwith one or another 'of said stop members according to the position ofsaidl lever, means for limiting the movement of said lever in oppositedirections respectively,

a coiled compression spring biasing said lever away from said basetoward one of its extreme positions, and means including' a reciprocablemember engageable with said lever between the point of pivotal supportthereof' and said contactor to eifect movement of the former towarditsother extreme position against the bias of said additional springmeans, said tension spring means being adapted upon such movements ofsaid lever toward opposite extreme positions to effect snap movements ofsaid contactor into engagement with said stop members alternately.

4. In an electric snap switch, in combination, an insulating base, asheet metal bracket secured to said base, a sheet metal lever having atone end thereof an open pivotal connection with said bracket, a sheetmetal contactor having an open pivotal connection with said lever at theother end of the latter, a pair of stop members ar-y ranged in spacedrelationship to each other and at opposite faces respectively of saidcontactor, at least one of said stop members comprising a stationarycontact. tension spring means interposed between said bracket and saidcontactor,

said spring means being adapted to bias said contactor. into engagementwith one or another of saidstop members according to the Aposition ofsaid lever, means for limiting the movement of said lever in oppositedirections respectively,

' additional spring means, said tension spring means being adapted uponsuch movements of said lever toward opposite extreme positions toeil'ect snap movements of said contactor into engagement with said stopmembers alternately, a wiring terminal member mechanically andelectrically connected with said bracket, and a wiring terminal membermechanically and electrically connected with said stationary contact,said wiring terminal members being exposed and readily accessible at thelower face of said base.

5. In an electric snap switch, in combination, an insulating base, asheet metal bracket secured to said base, a sheet metal leve;` having atone end thereof an open pivotal connection with said bracket, a sheetmetal contactor having an open pivotal connection with said lever at theother end of the latter, a pair of stop members arranged inspacedrelationship to each other and at opposite faces respectively ofsaid con-.

tactor, at least one of said stop members comprising a stationarycontact, tension spring means interposed between said bracket and saidcontactor, said spring means being adapted to bias said contactor intoengagement with one or another of said stop members according to theposition of said lever, means for limiting the movement of said lever inopposite directions respectively, a coiled compression spring biasingsaid lever away from said base toward` one of its extreme positions,means including a reciprocable member engageable with said lever betweenthe point of pivotal support thereof and said contactor to effectmovement of the former toward its other extreme position against thebias of said additional spring means, said tension spring means beingadapted upon such movements of said lever toward opposite extreme ipositions to effect snap movements of said contactor into-engagementwith said stop members alternately, a wiring terminal membermechanically and electrically connected with said bracket, a wiringterminal member mechanically and electrically connected with saidstationary contact, said wiring terminal members being exposed andreadily accessibleV at the lower face of said base, an insulating covermember superimposed upon said base and rigidly and permanently attachedthereto,-said cover member having an opening formed therein to provideclearance for said reciprocable member, and said cover membel` and saidreciprocable member having parts associated therewith to normally limitthe degrees of outward and inward displacement of said reciprocablemember and to insure against such a degree of inward movement thereof aswould cause injury to the switch parts. y

6. In an electric snap switch, in combination, an insulating base, abracket secured thereto, a lever having an open pivotal connection withsaid bracket, a contactor having an open pivotal connection with saidlever, tension spring means attached jointly to said bracket and to saidcontactor to maintain the aforementioned pivotal connections betweensaid parts and to bias said contactor toward one extreme position or theother according to the position of said lever, a pair of stop membersarranged above and below said contactor to limit the throw ofthe latterin eachl direction, a coiled compression spring interposed between saidbase and said lever to bias the latter away from the former, a screwhaving ad- Justable engagement with said base, the head of said screwoverlying said lever to limit the degree of movement thereof under saidspring bias, at least one of said stop members comprising a stationarycontact, a wiring terminal element electrically connected with saidcontact, a wiring terminal element electrically connected with saidbracket, said wiring terminal elements being exposed at the lower faceof said base, means comprising a movable member engageable with saidlever to eil'ect movement of the latter against lSaid spring biasthereof, said last mentioned means comprising a manually operablepushbutton supported relatively to said base, and said pushbutton havingspring means associated therewith to absorb any pressure applied theretoin excess of that required to eilect operation of the switch, wherebyinjury to the latter is prevented. i 7. In an electric snap switch, incombination, an insulating base, a bracket secured thereto, a leverhaving an open pivotal connection with said bracket, a contactor havingan open pivotal connection with said lever, tension spring meansattached jointly to said bracket and to said contactor to maintain theaforementioned pivotal connections between said parts and to bias saidcontactor toward one extreme position or the other according to theposition of said lever, a pair of stop members arranged above and belowsaid contactor to limit the throw of the latter in each direction, acoiled compression spring interposed between said base and said lever tobias the latter away from the former, a screw having adjustableengagement with said base, the head of said screw overlying said leverto limit .the degree of movement thereof under said spring bias, atleast one of said stop members comprising a stationary contact, a wiringterminal element electrically connected with said contact, a wiringterminal element electrically connected with said bracket, said wiringterminal elements being exposed at the lower face of said base, meanscomprising a movable member engageable with said lever to enact movementof the latter against said spring bias thereof, said last mentionedmeans comprising a manually operable pushbutton supported relatively tosaid base, said pushbutton having spring means associated therewith toabsorb any pressure applied thereto in excess of that required to effectoperation of the switch, whereby injury to the latter is prevented, saidbase having an insulating cover member attached thereto, and saidpushbutton having a part engageable with said cover member to positivelylimit the degree of movement of said movable member relatively to saidlever.

8. In an electric snap switch, in combination, a molded insulatingbasehaving a recess opening to the upper face thereof, a punched andstamped sheet metalbracket of substantially L-shape in cross sectionhaving one arm thereof rigidly and permanently secured to said base, awiring terminal member mechanically and electrically connected to saidbracket and exposed at the lowerface of said base, the other arm of saidbracket upstanding from said base and having notches formed in oppositeside edges thereof, a punched and stamped sheet metal lever having arelatively long flat portion notched atone end to provide a pair ofspaced lugs fitting into said bracket notches to provide an open pivotalconnection be# tween said parts, said upstanding bracket arm having avertical knife edge formed thereon and one wall of said lever notchbeing adapted to bear thereagainst, said lever having a perforated lugbent downwardly therefrom at the other end thereof, a punched andstamped sheet metal contactor having an integral lug adapted to fitloosely into the perforation in said lever lug to provide an openpivotal connection between said parts.

said contactor having integral arms extending from opposite side edgesthereof, a pair of coiled tension springs having hooked endsrespectively engaged with said contactor arms and with saidl bracket, apair of spaced stop members respectively arranged above and below thefree end of said contactor to limit the degree of movement of the latterin each direction, a coiled compression spring interposed between thebottom wall of said recess and said lever to bias the latter upwardlyfrom said bottomwall, said lever having an opening formed in said ilatportion thereof, a screw the shank of which extends downwardly throughsaid opening and is adjustably engaged with a threaded opening in thebottom wall of said recess, a portion of said screw shank being exposedwithin a. recess formed in the lower face of said base, and meansassociated with said exposed portion of said screw shank to restrain thesame agains turning in either direction after the desired degree ofadjustment thereof vhas been effected, said last mentioned meansincludinga body of insulating material located within said lastmentioned recess in contact with and concealing said portion of thescrew shank, at least one of said stop members comprising a stationarycontact, and wiring terminal means electrically connected with saidcontact and exposed at the lower face of said base.

9. In an electric snap switch, in combination. a molded insulating basehaving a recess opening to the upper face thereof, apunched and stampedsheet metal bracket of substantially L-shape in cross section having onearm thereof rigidly and permanently secured to said base, a wiringterminal member mechanically and electrically connected to said bracketand exposed at the lower face of said base. the other arm of saidbracket upstanding from said base and having lnotches formedin oppositeside edges thereof, a punched and stamped sheet metal lever having arelatively long flat portion notched at one end to provide a pair ofspaced lugs fitting into said bracket notches to provide an open pivotalconnection between said parts, said upstanding bracket arm having avertical knife edge formed thereon and one wall of said lever notchbeing adapted to bear thereagainst, said lever having a perforated lugbent downwardly therefrom at the other end thereof, a punched andstamped sheet metal contactor having an integral lug adapted to fitloosely into the perforation in said lever lug to provide-,an openpivotal connection between said parts, said contactor having integralarms extending from opposite side edges thereof, a pair of coiledtension springs having hooked ends respectivelyengag'ed with saidcontactor arms and with said bracket, a pair of spaced stop membersrespectively arranged above yand below the free end of said contactor tolimit the degree of movement of the latter in each direction. a coiledcompression spring interposed between the bottom wall of said recess andsaid lever to bias thel latter upwardly from said bottom Wall, saidlever having an opening formed in said flat portion thereof, a screw theshank of which extends downwardly through said opening and is adjustablyengaged with a threaded opening in the bottom wall of said recess, aportion of said screw shank being exposed within a recess formed in thelower face of said base, means associated with said exposed portion ofsaid screw shank to restrain the same against turning in eitherdirection after the desired degree of adjustment thereof has beeneifected,

said last mentioned means including a. body of insulating materiallocated within said last mentioned recess in contact with and concealingsaid portion of the screw shank, at least one of said stop memberscomprising a stationary contact, wiring terminal means electricallyconnected with said contact and exposed at the lower face of said base,a recessed molded insulating cover member rigidly secured to said base,said cover member having an opening formed therein, an actuating memberreciprocable within said opening and adapted forv engagement with'saidlever, and the length of such actuating member being such as to preventinjury tosaid switch mechamember to a plane ush with the upper end ofsaid opening in said cover member.

10. In a low travel limit switch, in combination, a molded insulatingbase, a substantially L-shaped sheet metal bracket having one armthereof secured ilatwise to said base, a sheet metal lever one end ofwhich has an open pivotal connection with the other arm of said bracket,a sheet metal contactor-carrier having an open pivotal connection withthe other end of said lever, tension -spring means respectivelyconnected with said carrier and said bracket to normally maintain theaforementioned open pivotal connections and to bias said carrier towardone extreme position or the other according to the position of saidlever, a pair of stop members arranged in spaced relationship to eachother at opposite faces of said carrier, said base being adapted tolimit the degree of pivotal movement of said lever in one direction, avcoiled compression spring interposed between said baseand said lever tobias the latter towardits other extreme position, a screw the shank ofwhich has threaded engagement with said base, the head of said screwoverlying aportion of said lever to limit the degree of movement of thelatter away from said base, said base having a recess in its lower faceintoV which a portion of said screw shank projects as an incident to thedesired adjustment thereof, said portion of said screw shank being bentwithin said recess to prevent movement of said screw head `away fromsaid base, and a body of self-hardening insulating material locatedwithin said recess and engaging the walls of the latter and said bentshank, to prevent inward drivi`ng of said screw after the aforementionedadjustment thereof has been effected.

11. In an electric switch, in combination, an insulating base, a metalbracket secured thereto, a. sheet metal lever having an open pivotalconnection with said bracket,- a contactor having an open pivotalconnection with said lever, spring means connected jointly with saidcontactor and said bracket to maintain ythe aforementioned pivotalconnections and to bias said contacter toward one extreme position orthe other according to the position of said lever, stop membersrespectively positioned in spaced relationship to each other at oppositefaces of said contacter to limit the throw of the latter in eachdirection, a spring associated with said lever tobias the free endthereof away from said base,'a screw having adjustable engagement withsaid base, said screw having a head overlying-said lever to limit thedegree of movement of the latter under the bias of said last mentionedspring, at least one of said stop members comprising a stationarycontact, wiring terminal elements respectively electrically connectedwith each contact and with said bracket, and means comprising a movablemember engageable with said lever to eil'ect movement oi the latteragainst the joint action of all of said biasing springs.

12. In an electric switch, in combination, an insulating base, a sheetmetal bracket secured to said base, a sheet metal lever one end of whichhas an open pivotal connection with said bracket, a sheet metalcontacter-carrier having an open pivotal connection with the other endof said lever, spring means associated with said carrier and saidbracket to normally maintain the aforementioned open pivotal connectionsand to bias said carrier toward one extreme position or the otheraccording to the position of said lever. a pair of stop members arrangedin spaced rela-v tionship to each other at opposite faces of saidcarrier, said base being adapted to limit the degree of pivotal movementof said lever in one direction, additional spring means interposedbetween said base and said lever tobias the latter toward its otherextreme position, a screw the shank of which has threaded engagementwith said base, the head of said screw overlying a portion of said leverto predetermine the. last mentioned extreme position of the latter, anda portion of the shank of said screw extending through said base andbeing bent to effectively prevent movement of said screw head away fromsaid base.

13. In an electric switch, in combination, an insulating'base, a sheetmetal bracket secured to said base, a sheet metal lever one end of whichhas an open pivotal 'connection with said bracket,

'a sheet metal contacter-carrier having an open pivotal connection withthe other end of said lever, spring means associated with said carrierand said bracket to normally maintain the aforementioned open pivotalconnections and to bias said carrier toward one extreme position or theother according to the position of said lever, a pair of stop membersarranged in spaced relationship to each other at opposite faces of saidcarrier, said base being adapted to limit the degree of pivotal movementof said lever in one direction, additional spring means interposedbetween said base and said lever to bias the latter toward its otherextreme position, a screw the shank of which has threaded engagementwith said base, the head of said screw overlying a portion of said leverto predetermine the last vmentioned extreme position of the latter, aportion of the shank of said screw extending through said base and beingbent to effectively prevent movement of said screw'head away from saidbase, and a body of self-hardening cement adapted to jointly adhere tothe bent portion of said screw shank and saidI base to effectivelyprevent inward movement of said screw after the aforementionedadjustment of the latter.

GEORGE J. MEUER.

